Computer databases are used for the storage and rapid retrieval of large amounts of data. Typically, a computer database includes a computer which executes a database program to write to and read data from a large computer accessible memory. The particular data read from the memory is determined by a user query. In response to the user query, the database produces a report listing database data having selected characteristics.
For example, a university may use a computer database to store information about its students and courses. In response to a user query, the computer database can generate a report indicating the names of the students in particular courses. In order to produce this report, the database must record not only student names and courses ("attributes") but also "relations" between the attributes--in this example, which students "attend" which courses.